Wheelchair lifts have been mounted directly to vans, trucks and buses for many years providing disabled individuals with better access to transportation, increasing their mobility and permitting them to achieve a more self-reliant, fully functional lifestyle. One such wheelchair lift is described in the patent to Deacon, U.S. Pat. No. Re. 31,178 wherein a vehicle mounted device for moving a wheelchair and its occupant to and from the inside of a vehicle is described.
In particular, the Deacon lift has a pair of parallelogram linkages, one mounted at each side of an access opening of a vehicle and extendable outwardly from the access opening. Each parallelogram linkage includes an upright support post that is mounted to the floor inside the vehicle. Each linkage also includes a vertical end post which is pivotally connected to the upright support post by a pair of parallel arms. A platform for receiving the wheelchair is mounted between and at the lower ends of the vertical end posts. A driveshaft with two sprocket and chain drives, one at each end of the shaft, is mounted on and between the upper ends of the upright support posts for operating each parallelogram linkage. In operation, the linkages move such that the platform is maintained in a substantially horizontal position as it is moved from the ground to the access opening adjacent the floor of the vehicle and vice versa.
A problem with the Deacon lift is that the driveshaft between the upper ends of the upright support posts restricts the headroom available when a wheelchair user enters the vehicle through the access opening. Preferably, the support posts of the lift are designed to extend above the top of the access opening such that the driveshaft is as high a possible. Achieving this solution, however, requires each lift to be specially designed and fabricated to take into account the door size of the particular model van, truck or bus to be fitted. Furthermore, the lift may be used either with the rear door opening or the side door opening of the van. The height of these openings, however, may also be different depending on the particular model, again requiring a specially made lift.
Accordingly, a need has arisen for a standardized wheelchair lift that is adaptable to a variety of vehicles regardless of the size access opening the particular vehicle may have. Such a lift would permit easier and safer access for a wheelchair user. It would also maximize headspace inside the vehicle which would allow a wheelchair user to more easily carry long or bulky items on or off the vehicle. Installing the lift to the vehicle would also be easier in that the upper ends of the support posts, being above the door opening and nearer the roof of the vehicle, may be secured to the door header or anywhere along a vertically extending doorpost. Additionally, if a vehicle required upgrading, e.g. enlargement of the access opening, or if a new vehicle were purchased, the same lift could be reinstalled onto the upgraded or new vehicle. Finally, a standardized lift would permit retail dealers to carry a number of lifts in inventory, eliminating the waiting period which was previously necessary for manufacturing and shipping a specially designed lift. Similarly, a manufacturer need not design or plan for as wide a range of lifts to account for the many possible variations of vehicles.